It's basically fast-acting arthritis in the first joint of the big toe. No one really knows what causes it.

Quoting: The Guy

That's what they always say when they want to do surgery and prescribe drugs that dont work. They have no other answers.

I has a finger that would not bend. Had a sharp pain. It was all of a sudden; I thought it was broken. I did not run right out to the doctor. I did put the finger in a store bought splint for 2 weeks assuming maybe it was weak or broken. Did not help. Next I just began to bend the finger more every day and soon it was back working with no pain. Today it is completely normal.

Just goes to show the old saying "use it or lose it."

I had been typing on a keyboard instead of swinging a construction hammer and after a while of not bending the fingers stiffened. Same with toes.

There could be other dietary factors also since some foods do promote arthritic bone lose; these too are reversible.